Process for improving the tensile strength of gray cotton yarn



Patented May 31, 1949 PROCESS. FOR IMPROVING THE TENSILE STRENGTH OF GRAY COTTON YARN Luther Axford Clifton, N. 1., assignor to United States; Rubber. Company, New York, N. in, a corporation. of. New Jersey No-Dliawing Application June 21, 1947, Serial No. 756,323

6 Glaims. 1

This invention relates to treatment of cotton yarns in such manner as to substantially prove their tensile strength, and to the product of such treatment.

Ithas been proposed to treat cotton strands to improve their tensile strength. by a two-bath process in which. the strands are first treated in an aqueous bath which preferably slightly alkaline, for example a bath. of aqueous am.- monia, and thereafter treated in a bathof an organic liquid having the property of dissolving cotton waxes, preferably a bath of amyl acetate at a temperature above 25 C. but not in excess of- 150 C., the resulting strands thereafter being dried to remove the solvent. Such a; processis disclosed and claimed in, the co-pending application of Hendrik Romeyn=, Jr;, SeriahNo; 600:;902, filed June 22; 1945. While such a process is very eiiective in increasing the tensile strength of' the strands, a single bath treatment would matea ly duc quipmen and labo o t The principal object of the; present invention is to provide an. improved method ofincreasing the tensile strength, of rey cotton yarns. Another object is; to provideas a new article of manufacture grey cottonyarn of. lmprovedtensile strength. Another object is to bring about the improvement. in tensile strength of the cotton yarn with a single bath process. Another object is to provide a simple and economical method. of

increasing the tensile strength or grey; cotton yarn with the employment of only a single treating bath. Many other objects; will more fully hereinafter appear.

I have discovered that thetensila strength of grey cotton yarn may be substantially improved in a simple, and commercially attractive manner by contacting the yarnv with a, hot; aqueoussolution comprising from 10 to 50% of water, and correspondingly from 90 to 50% of a saturated monohydric aliphatic, alcohol which contains from 3 to 5 carbon atoms per molecule and which, is capable of dissolving, water at 75 to 95 C; to the extent of at least parts of water per 100 parts by weight of the solution, tensioning the yarn while still hot and wet. with said solution, and drying the resulting yarn under tension.

The process 01 my invention is carried out at h-Wi in. a impl nd. economi a manner. by immersing packages of the yarn in. the hot aqueous alcoholic bath for the desired period of time, preferably with circulation of the hot solution through the packages in a 'suitableknown manner, as for example by-the use; of spoolshaving a perforated barrel plugged at. one end. and the application. of suction to the inside of the perforated barrel to effect the desired circulation. The yarns are then subjected to tension while they are still hot and wet, for example by rewinding onto other spools. The resulting packages may thenbedriedinany suitable manner.

As is customary in the art, the term grey cot.- ton as used herein refers to cotton containing substantially all natural cotton waxes, which are that group or" non-cellulosic water-insoluble components of grey cotton which are charaoterized by very high solubility in hot ethyl, alcohol;

The C3 to C5 alkanols, i. e., saturated mono hydric aliphatic alcohols, which are. employed; in accordancewith the present invention. are n.-.pr.opyl, isopropyl, n-butyl, sec. butyl, isobutyl, tert. butyl, sec. amyi and tertiary amyl alcohols and mixtures of said alcohols. Only these alcohols and mixtures thereof meet theabove requirement as to capabiiity oidissolving Water at tempera.- tures of to 95 C. Aqueous solutions or methyl and ethyl alcohols do not give improvements in tensile strength or grey cotton yarn comparable with those obtained with aqueoussolutions of the alcohols spec; ed for use in accordance with the present-invention. n-Amyl and isoamyl' alcohols andalcohols-containing more than 5-carbonatoms per molecule and polyhydric alcohols are unsuitable because they have too low a miscibility with water and/ or because they have too low a vapor pressure to permit drying ina practical length of time.

The concentration of the selected C3 tO-Cs alcohol in the aqueous treating bath may range anywhere from 50 to by weight. Thepreferred range is from 55 to 60% by weight of alcohol. Treating baths containing from 55 to- 80% of tort. butylalcohol or of 2-propan0l (isopropyl alcohol) the balance being essentially water, are. particularly attractive commercially for usein the present invention.

Any suitable method of carrying out the liquidcontacting step of the present invention maybe employed. Since the purpose of thestep is to secure the maximum degree of penetration of the treating bath into the fibers, preference is given to those methods which effect substantially complete saturation of the yarns. The contacting may conveniently. be effected by immersing the spooled single yarn into the aqueous bath for the desired period of time. As stated above, it ispreferred to provide means for circulating the solution through the spooled yarn. The. maximum improvements are obtained when the. temperature of the aqueous alcoholic bath is maintained at or near the boiling point of the azeotrope of water and the selected alcohol, via, in the range of from 7:5 to C. The temperature used; in the contacting step may range from 60 to.95'C. At temperatures below 60 C. the improved yarn is. not produced in a reasonable length of time,

The amount of solution relative to the amount of yarn. being treatedmay vary within, wide limits. For example, the amount of solution sucked through the package of yarn may be as: little as one liter per pound of cotton, but more may be drawn through without adverse effect, The; time of contact with the liquid should be sufficient to secure complete penetration of the solution through the yarn and may vary from five minutes up to an hour.

While still hot the wet yarn is subjected to substantial tension, and is rewound and dried under tension. The extent of tensioning may vary within wide limits, but I prefer to employ a tension ranging from 50% up to 75% of the breaking strength of the untreated yarn. (The breaking strength of the untreated yarn is conventionally measured at 65% relative humidity and 70 F.) The temperature to which yarn is subjected during the wet tensioning operation is preferably of the same order as that maintained during the contacting step, namely from 60 to 95 C. and preferably at or near the boiling point of the azeotrope of water and the alcohol, namely 75 to 95 C. Following the wet tensioning step, the rewound yarn is dried under substantial tension at a temperature sufficiently high to volatilize all of the treating liquid from the yarn. Conveniently the spooled rewound wet yarn is simply dried on the spool, as I have found that the yarn is maintained at suificient tension under these conditions.

The improvement in tensile strength of the yarns when treated in accordance with the present invention is independent of and unrelated to dewaxing of the fibers. This is illustrated, for example, in Example 2 below wherein 100% 2-propanol is seen to give much less improvement in tensile strength than aqueous 2-propanol solutions containing from 50% to 90% of 2-propanol, although the 100% propanol will effect more extensive dewaxing than the aqueous propanol solution. In practice, the cotton yarn after the treatment of the present invention usually contains at least 40% of the ethanol-extractable material initially present.

The treated yarns of the invention may be further fabricated to give new products exhibiting greater strength; for example, sewing thread and woven fabrics may be constructed from treated single yarns. The yarns obtained by the treatment of the present invention are characterized by a tenacity which is from 50% to 83% greater than that of the untreated yarn.

It is well known that the strength of cotton yarn can be increased to some extent, 1. e. about 10% to 25%, by tensioning it while wet with water. See for example Burgeni, United States Patent 2,173,997. It is also well known that the strength of cotton yarn can be increased up to 25% by repeated treatment with hot benzene, carbon tetrachloride or other organic solvents which are substantially immiscible with water. However my process is novel in its use of an aqueous solution of selected C3 to C5 aliphatic saturated monohydric alcohols. In view of the prior art it is unexpected that such an aqueous solution should have so extraordinarily favorable an effect on the tensile strength. If, as suggested by the prior art, the beneficial efiect were due to the extraction of waxes it would be expected that the greatest efiect would be obtained when the strength of the alcohol solution was increased to 100%. Furthermore, as is shown in Example 2 below, the improvement when an aqueous C3 to Ca alcohol mixture containing from 50% to 90% of alcohol is used is much greater than the sum of the improvements due to water alone and due to the alcohol alone.

The following examples illustrate the process. In all cases the measurements of tenacity were '4 made on yarn which had been conditioned at 65% relative humidity at 70 F.

Example 1 A 3000 yard length of grey 7.6/1 cotton yarn wound on a metal spool with a perforated barrel is immersed in a hot bath consisting of 45% of water (by weight) and 55% of tertiary butyl alcohol maintained at about C. The barrel is stoppered at one end. The solution is drawn through the package by means of a vacuum applied to the other end. It has been my practice, but by no means a limitation, to draw through about 1 liter of solution per pound of cotton. The package is then removed from the bath and the yarn respooled under a tension of 27 oz. After this respooling the package is dried while still under tension on the spool at 100 C. for one hour or more, until the yarn is free of alcohol. I-Iot air may be drawn through the spool in the oven to hasten the drying.

Yarn so treated shows a 76% increase in tenacity and a reduction in stretch as illustrated by th following test data:

Grey 7.4/1 yarns were treated as in Example 1, except that the alcohol component of the bath was 2-propanol and that variations were made in the concentration of the bath. The results are shown in the following table.

Com la3osgtnion of In a crease Ten- Tenacity Stretch sile in G/D THEORY at Break Alcohol Water Percent Percent 0 0 6, 310 2. 86 1.83 .04 0 100 7,166 2. 94 2.14 16.9 2. O3 36 64 6, 755 3. 23 2. 22 21. 3 2. 42 45 55 6, 750 3. 70 2. 54 38. 7 2. 54 55 45 6, 850 4. 62 3. 22 75. 5 3. 21 60 40 6, 670 4. 33 2. 93 60. 2 2. 59 70 30 6, 580 4.50 3.00 64. 0 2. 63 80 20 6, 530 4. 41 2. 92 59. 5 3. 39 10 6, 485 4. 23 2. 78 51. 9 3. 68 0 6, 610 3. 06 2. 06 12. 6 4. 50

These results show that aqueous 2-propanol solutions containing 10% to 45% of water and 55% to 90% of 2-propanol are far more effective in raising the tenacity of the yarn than either water or the alcohol alone.

Example 3 Grey 7.6/1 cotton yarns were treated with tertiary butyl alcohol as described in Example 1, variations being made in the concentration of the bath as noted below.

These results (in conjunction with the results with water alone as shown in the preceding example) show that the-45:55 water and alcohol mixtur g-i-vessubstantially greater improvement Polyhyd-r-ic alcohols are unsuitable because they have too low a vapor pressure to permit drying in a practical length of time and they are retained in the cotton yarn, producing poor tenacity despite good improvement in strength. The following data will illustrate this.

in tensile strengthand tenacity than does either component alone.

Oomp.- of -B ath Ethylene Improvement Tert Butyl Glyc 01 Glycerme Yds./lb. Strength Stretch G/D in G/D Am Water Percent 33 33 6, 137 3. 93 4. 33 2. 45 42.

50 4, 618 3.07 4.09 1.44 16. 3 33 33 33 5, 846 3. 91 5.07 2. 32 34. 8 50 50 6, 363 3. 93 4.09 2. 54 47. 6 ,55 .45 (Control) 6, 900 4. 32 3. 08 3. 03 76 Grey 6, 485 2. 61 7. 29 1. 72

Example 4 J acoby (United States Patent 1,398,378) extracts with benzene and. obtains a product 57.4/1 cotton yarns were treated as described in stronger. Following the teachings of Jacoby,

.Example 1 except that other alcohols were evaluated. 7.6/1 cotton yarns were treated as in the present Bath Comp.

. Increase Alcohol Yds/lb. Tensile g g iig in g' fss Alc. H2O Tammy Per cent Per cent 0 0 6,310 2. so 1.83 e. 04 "Tertiary-army] so 20 e, 600 4. 37 2. 93 2. so .n Butyl- 70 6,990 4. 7s a. s5 2. 5s n-Propy 55 e 740 4.36 2.98 2.60

,The alcohols in this example effect a remarkable .increase in the tenacity, just as in the case of the-other alcohols shown.

lMonohydricalcohols which do not give com- Example 1 except that: (a) Hot benzene solvent was used at a temperature of 78 0.; and (b) half of the package was subjected to tension and the remaining half was not tensioned.

Improve- Bath Yds./lb. Strength Stretch G/D ment in Percent Percent Tensioned yarn. Benzol 78 0.. 6,404, 3.02 4. 6 1. 96 7 N0 tension do 6, 264 3. 45 7. 2 2. 20 2O From the foregoing description many advantages of the present invention will be apparent to those skilled in the art. The principal advantage of the invention is that by its practice it parable improvements are methyl and ethyl alcohol. The data below illustrate the lesser efiects obtained bythe use of methyl alcohol with and without water.

is .possibleto treat grey cotton yarn in a simple one-bath process to obtain new textile materials havingv greatly increased strength. As compared The following data illustratethe lesser effects .obtained by the useof ,ethyl alcohol with and without vwater.

Composition 0! Bath 1m prove- Yds./lb. Tensile Stretch II:enaclty ment in G/D in G) Alcohol Water Per cent Grey yarn 6, 360 3. 18 6. 35 2. 06 Control using to ary butyl a1 6, 774 4. 77 3. 20 3. 30 60. 3 7, 073 3. 48 2. 28 2. 50 21. 4 6, 718 4. 14 3. 12 2. 83 37. 4 6, 370 4. 33 3. 96 2. 36. 2 6, 768 4. 25 3. 97 2. 92 41. 8 6, 220 4. 41 4. 40 2. 80 35. 9

to other currently employed processes, this invention produces a greater increase in strength without the use of excessively high tension or prolonged washing and without the additional steps necessary in a, two-bath treatment. A further advantage is the relative ease with which the process of the present invention is applied to light single yarns from which a variety of twisted yarns, cords and woven fabrics may be prepared. Many other advantages of the present invention will be obvious to those skilled in the art.

All percentages and parts referred to herein are by weight.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. lhe process of improving the tensile strength of grey cotton yarn which comprises saturating the yarn with a hot aqueous solution comprising from 10 to 50 per cent of water and correspondingly from 90 to 50 per cent of a saturated monohydric aliphatic alcohol which contains from three to five carbon atoms per molecule and which is capable of dissolving water at 75-95 C. to the extent of at least 10 parts of water per 100 parts by weight of the alcohol and water solution, said solution being at a temperature of from 60 C. to the boiling point of said solution, tensioning the yarn while it is hot and wet with said solution at a temperature of from 60 C. to the boiling point of said solution and under a tension of from 50% to 75% of the breaking strength of the untreated yarn measured at 65% relative humidity and 70 F., and drying the resulting yarn under substantial tension at a temperature sufiiciently high to volatilize all of said solution therefrom.

2. The process of improving the tensile strength of grey cotton yarn which comprises saturating the yarn with a hot aqueous solution comprising from 20 to 45 per cent of water and correspondingly from 80 to 55 per cent of a saturated monohydrlc aliphatic alcohol which contains from 3 to 5 carbon atoms per molecule and which is capable of dissolving water at 75-95 C. to the extent of at least parts of water per 100 parts by weight of the solution, said solution being at a temperature of from 60 C. to the boiling point of said solution, tensioning the yarn while it is hot and wet with said solution at a temperature of from 60 C. to the boiling point of said solution and under a tension of from 50% to 75% of the breaking strength of the untreated yarn measured at 65% relative humidity and 70 F., and drying the resulting yarn under substantial tension at a temperature sufficiently high to volatilize all of said solution therefrom.

3. The process of improving the tensile strength of grey cotton yarn which comprises saturating the yarn with a hot aqueous solution comprising from to 45 per cent of water and correspondingly from 80 to 55 per cent of tertiary butyl alcohol, said solution being at a temperature of from 60 C. to the boiling point of said solution, tensioning the yarn while it is hot and wet with said solution at temperature of from 60 C. to the boiling point oi said solution and under a tension of lfIOll'l 50% to 75% of the breaking strength of the untreated yarn measured at relative humidit and 11, and drying the resulting yarn under substantial tension at a temperature sur'liciently high to volatilize all of said solution therefrom.

i. The process of improving the tensile strength of grey cotton yarn which comprises saturating the yarn with a hot aqueous solution comprising from 20 to 45 per cent of water and correspondingly from to 55 per cent of Z-propanol, said solution being at a temperature of from 60 C. to the boiling point of said solution, tensioning the yarn while it is hot and wet with said solution at a temperature oi from 60 C. to the boiling point of said solution and under a tension of from 50% to 75% of the breaking strength of the untreated yarn measured at 65% relative humidity and 70 F., and drying the resulting yarn under substantial tension at a temperature sufficiently high to volatilize all of said solution therefrom.

5. The process of claim 1 wherein said solution is maintained at a temperature near the boiling point of the solution during said saturating step.

6. The process of improving the tensile strength oi grey cotton yarn which comprises immersing the yarn wound on a package in an aqueous solution comprising from 10 to 50 per cent of water and correspondingly from to 50 per cent of a saturated monohydric aliphatic alcohol which contains from three to five carbon atoms per molecule and which is capable of dissolving water at 7590 C. to the extent of at least 10 parts of water per 100 parts by weight of the solution, maintaining said solution at a temperature of from 75 to C. during said immersing step, circulating said solution through said package for such a period of time that the yarn is completely saturated with said solution, rewinding the yarn onto another package while it is wet with said solution, under a tension of from 50 to 75 per cent of the breaking strength of the untreated yarn measured at 70 F. and 65 per cent relative humidity, and drying the resulting package while maintaining the yarn thereon under the resulting tension at a temperature sufficiently high to volatilize all of said solution therefrom.

LUTHER AXFORD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,173,997 Burgeni Sept. 26, 1939 2,178,743 Dreyfus et al. Nov. 7, 1939 2,364,467 Nickerson Dec. 5, 1944 

